The future MPEG-7 standard is intended to provide a flexible and extensible framework for defining a standard set of descriptors that can be used to describe various types of multimedia documents. The description thus associated with a given content allows fast and efficient searching for material of a user's interest. The invention relates more specifically to the case of representation of video sequences.
A video sequence is a series of sequentially ordered images (in time). Prior to its storage in a database, the corresponding videostream is segmented into elementary units (or shots, a shot being a sequence of contiguous frames generated during a continuous operation and representing a continuous action in time and space), that are then identified and indexed. A video indexing technique is described for instance in the document “Automatic video indexing via object motion analysis”, J. D. Courtney, Pattern Recognition, volume 30, number 4, April 1997, pp.607-625. As explained in said document, the logical organization of video 'sequences may be determined by means of a hierarchical segmentation, in the same manner a text is subdivided into chapters and paragraphs. However, in many cases, this temporal segmentation seems to be not completely appropriate, for instance in applications such as sport (soccer, tennis games) where video shots can be very long.